One easy(-ish) way of creating realistic water to use more than one bump map. I don't mean just within DTE (as above), but within the materials lab select 2 or 3 dots (materials) instead of just the one (hold down CTRL and drag the mouse over the dots). Doing this and varying the % coverage size on each material you can produce all sorts of effects, like areas of windy waves on a calm lake, etc. Use the same method with diffusion too, if you're brave. You can use this method to disguise repeating JPG textures as well. Mix your bumps and diffusions on the JPG with procedural textures and you need never worry about repeating patterns again! ;) Maybe a bit of an exaggeration, but for subtle patterns it does work!